Apron for scraper



Oct. 31, 1961 J. M. LAYTON APRON FOR SCRAPER Filed June 4, 1958 AT TOR/V5 Y United States Patent 3,606,:988 APRGN FUR SCRAEER John M. Layton, Howell, Mich, assignor to General 1 iotors Corporation, Detroit, Mich, a corporation of Delaware Filed lune 4-, 12 53, Ser. No. reason 7 Claims. (til. 37-12?) This invention relates to tractor-drawn scraper bowls of the type having an open front for receiving and discharging material and, in particular, to an apron and its operating mechanism for not only controlling receipt and discharge of material through the open bowl front but also to facilitate the digging operation.

Conventional digging and carrying scrapers normally include a tractor drawing a bowl having a fioor and laterally spaced side walls defining an open bowl front. An apron is pivotally connected to the bowl side walls and is adapted to be lowered over the open bowl front to retain materials within the bowl, or elevated to a position permitting the contents of the bowl to be discharged through the open front or a new load of material to be dug and received by the bowl.

As such a scraper bowl begins to dig, the material being dug by the bowl cutting edge flows rather easily into the bowl to be retained therein. However, as the bowl begins to fill, the material being dug begins to pile up in front of the cutting edge resulting not only in less rapid filling of the bowl, but also increased resistance to forward movement of the scraper unit and, therefore, an increase in power requirements.

It is, therefore, a primary object and feature of this invention to provide means for adapting a bowl apron of the type heretofore used merely as a load-retaining means for use as an auxiliary loading implement which will facilitate the loading operation of the bowl as well as conserve the power requirements of the prime mover.

Additionally, it is another object and feature of this invention to provide an auxiliary apron-controlling mech anism which may be locked or latched to retain the apron in an adjusted position irrespective of a primary operating means connected to the apron for lifting and lowering the latter relative to the open front of the bowl.

It is yet another object and feature of this invention to provide an apron mechanism for the open front of a scraper bowl, and which apron mechanism includes fluidactuated operating means acting on the apron to adjust and retain the latter in a plurality of positions relative to its support on the scraper whereby the lower edge of the apron may be disposed forwardly of the scraper cutting edge and, upon actuation of the means aforementioned, may be pivoted to propel materials piling up in front of the cutting edge into the bowl thereby facilitating loading of the latter.

These and other features, objects and advantages of this invention will appear more fully hereinafter as the description of the invention proceeds, and in which reference is made to the following drawings in which:

FIGURE 1 is a side elevation of a digging and carrying scraper equipped with this invention;

FIGURE 2 is a fragmentary plan view of the scraper bowl of FIGURE 1; and

FIGURE 3 is a fragmentary side elevation corresponding to FIGURE 1 showing the scraper bowl with its apron disposed in a position closing the bowl front.

Referring now to the drawings, the scraper unit may be seen to include an overhung tractor 2 supported on the ground-engaging wheels 4, a drawbar or pull yoke structure 6 and a bowl structure 8 having a rearward portion of its frame supported on the ground-engaging wheels 1t).

The drawbar structure 6 includes a pair of rearwardly diverging, upwardly arched arms 12 forming a gooseneclr, the forward end of the gooseneck being pivotally connected to the tractor on a vertical hitch and steering axis indicated at 14 while the rearward portion of the gooseneck is rigidly secured to a transversely extending torque tube 16 from the ends of which the laterally spaced arms is extend rearwardly for pivotal connection to the bowl side walls on a transverse horizontal axis indicated at 20.

The scraper bowl includes the transversely spaced side walls 22 upstanding from a transversely extending floor or pan 2d the forward edge of which is equipped with a transversely extending cutting edge or blade 26. A suitable selectively movable ejector, not shown, forms the rear wall of the scraper bowl and is actuable to discharge material therefrom through the open front defined by the forward edge of the floor 24 and spaced side walls 22. Such ejector structures are well known and may take the form of a member extending between the side walls 22 for reciprocating movement along floor 24-, or it may take the form shown in the United States Patent 2,773,320 issued to E. R. Fryer et al. in which the ejector structure is pivotally mounted to the bowl structure and forms the floor of the bowl as well as its rear wall.

The cutting edge 26 of the scraper bowl is adapted to be disposed in a digging position as shown in the drawings or raised therefrom into a carrying position by means of relative pivoting movement of the scraper drawbar 6 and bowl 8 about the axis 29. To this end, a pair of longitudinally extending levers 28 have their forwardmost ends suitably pivotally connected to the goose neck portion of the drawbar at El), and extend rearwardly for pivotal connection at 32 to depending rigid rods 34 having their lower ends operatively secured to a transversely extending frame member 36 at the forward portion of the scraper bowl. Suitable fiuid-operated jacks 38 have their lowermost ends pivotally connected within the torque tube 16, and their uppermost ends pivotally connected at 40 intermediate the ends of the levers 28, whereby the jacks 38 are operable through the levers 28 and rods 34 to lift and lower the scraper bowl between digging and carrying positions.

It is not considered necessary to furnish further details as to the general arrangement of the structure shown in the drawings inasmuch as the particular scraper con struction depicted is merely illustrative of one type of construction with which the apron mechanism to be described may be employed. If further details are desired with respect to the specific features of the scraper shown in the drawings, reference may be made to the aforementioned United States Patent 2,773,320. In any event, as the description of the apron and its operating mechanism proceeds, it will be readily apparent that this is but one type, although a preferable one, of scraper with which the apron may be employed.

The transversely extending apron 42 includes a curved lower portion having secured to the side edges thereof laterally spaced rearwardly extending plates 44. The apron is adapted to be adjustably supported on the scraper bowl by means of laterally spaced apron-supporting arms as each having its rearward end pivotally connected to a bowl side wall 22 on a transverse horizontal axis indicated at 48 which, of course, is parallel to the axis of connection 2! between the yoke arms 18 and the bowl side walls. The supporting arms 46 extend forwardly from the bowl side walls and are pivotally connected on a transverse horizontal axis indicated at 49 to the laterally spaced arms 5% rigidly secured to the apron. A pair of double acting fluid-operated jacks 52 of the piston and cylinder type form an adjustable operating and latch mechanism between the upper ends of arms 5% and each bowl side wall. To this end, the respective jack cylinders 54 are pivotally connected to the bowl side Walls 22 coaxially with the pivot axis 48 on which the arms 46 are supported. The reciprocable pistons within the cylinders 54 include a piston rod ss extending outwardly for pivotal connection at 58 to the upper end of the apron arms 5% An apron raising and lowering mechanism is provided on the drawbar 6 for lifting the apron from the closing position shown in PEG. 3 to a position in which the aforementioned ejector may discharge materials from the bowl or, alternatively, the bowl may be lowered into a digging position to receive a load. This apron control mechanism preferably takes the form of a lever as suitably pivotally connected at its forward end 62 to the gooseneck of the drawbar 6, and having a pulley 64 rotatably supported on its rearward end over which there is received a run of cable 66 having one end fixed to the 'drawbar as indicated at 68 and the other end secured to the lower portion of the apron as by a bracket "iii. A reciprocating piston and cylinder type jack '72 has its lower end pivotaliy con ected within the torque tube 16 and its upper end pivotally connected intermediate the ends of the lever 65 As will be obvious, extension of the jack 72 will pivot the lever 6% thereby resulting in raising movement of the apron 42 from the closing position shown in FIG. 3.

The operation of the apron mechanism will now be described. Prior to the beginning of a digging cycle, the bowl iift jacks 33 will be extended thereby carrying the scraper bowl at a suitable elevation in which the cutting edge 26 is out of contact with the ground. During this time, the apron will close the front of the scraper bowl by reason of the jack 72 being retracted. At the start of a digging operation, the bowl lift jacks 38 will be retracted to lower the cutting edge 26 into engagement with the ground as indicated in FIG. 1, and the apron lift jack 72 is extended to elevate the apron. At this time, or subsequently if desired, the jacks 52 are retracted to pivot the apron 42 relative to the supporting arms 46. At this time it will be appreciated that the lower edge of the apron is out of contact with the ground by reason of the fact that the apron lift levers is in an upward position. As the cutting edge 26 digs into the ground, the material is spilled into the bowl and begins to heap therein. As digging continues and the load in the bowl becomes larger, the material has a tendency to pile up in front of the cutting edge as indicated in FIG. 1, resulting in decreased loading speed and increased resistance to forward travel of the scraper. At this time, the apron lift jack 72 may be retracted, it being remembered that the jacks 52 have previously been retracted, thereby disposing the apron in the position shown in FIG. 1. Thereafter, the jacks 52 may be extended thereby pivoting the apron 42 about the pivot axis 49 which causes the lower end of the apron between the plates 44 to scoop the material enclosed between it and the cutting edge 26 into the scraper bowl. Upon the jacks 52- reaching the limit of their extending movement, the apron will be disposed in the position shown in FIG. 3 with its lower edge in substantial engagement with the cutting edge 26 thereby closing the open front of the bowl to retain the load therein. Thereafter the bowl may be raised to a carry position to transport the load to a discharge area.

From the above description of the operation, it will be readily apparent that the jacks 52 form an operating means for pivoting the apron 42 about its supporting arms 46 to scoop material from in front of the cutting edge 26 into the scraper bowl thereby resulting in the advantages aforementioned. Additionally, the jacks 52 act as fluid latches retaining the apron in any given adjusted position with respect to its support arms 46. Consequently, the apron lift mechanism including the lever 60 and cable 66 may function substantially in a conventional manner as set forth particularly in the aforementioned patent to Fryer, irrespective of the adjusted position of the apron. As a consequence, upon elevating the bowl to a carry position and with the apron pivoting mechanism including jacks 52 disposed as shown in FIG. 3, the bowl lift levers 28 can be pivoted counterclockwise to provide maximum high lift for the apron to open the bowl front fully for maximum rate of discharge of material therethrough. However, even a greater discharge area through the open bowl front can be obtained by utilizing the auxiliary apron adjustment mechanism of this invention by retracting the jacks 52 while the apron lifting lever 6d is in a high lift position. In this regard, it will be observed that the cable 66 forms a flexible connection between the lever (at? and apron 42 so as not to interfere with relative pivoting movement between the apron and its support arms 46.

?articular note may also be taken of the disposition of the respective jacks 52 relative to the apron and the side walls of the scraper bowl. in this regard, the cylinders 54 are pivotally connected to the bowl side walls 22, and the piston rods 56 are connected to the arms 50 of the apron for a particular purpose. Insofar as pivoting the apron relative to its supporting arms is concerned, it will be apparent that maximum thrust from the jacks 52 is desired in pivoting the apron from the FIG. 1 to the PEG. 3 position because of the resistance of the material being scooped into the bowl. Because the jacks are disposed as shown, this maximum thrust is obtained by reason of fluid emitted to the interior of the cylinders 54 having the full face of the piston therein to act against, as compared to reverse actuation of the jacks in which the area of the piston acted against by the fluid is reduced by the diameter of the piston rods 56. Furthermore, with the jacks 52 locked in a particular adjusted position, another condition of maximum force is required to resist retraction of the jacks 52 as the cable 66 is actuated to pull up on the apron. Again, the full area of the pistons opposite the piston rods 56 is acted upon by the fluid etween it and the cylinders to resist any tendency of the apron to pivot clockwise relative to the axis 49 on the supporting arms 46.

The various fluid-actuated jacks, including double-acting apron pivoting jacks 52, may be selectively controlled by various fluid systems well known in the art and therefore not shown. For example, a typical system utilized with scrapers would include an engine-driven pump supplying hydraulic fiuid to a control valve housing in which plural valves are positioned for controlling actuation of the respective jacks. Such well known valve mechanisms are of the type which, in a neutral position, lock fiuid in the various conduits leading to the jacks thereby maintaining the latter and the structure to which they are connected in a hold position.

Having disclosed an illustrative form of the invention, it is to be understood that this disclosure is not intended in any way to limit the scope of the invention which is defined by the claims which follow.

I claim:

1. A vehicle comprising a drawn scraper bowl having laterally spaced side Walls upstanding from a transversely extending floor and defining therewith an open bowl front for receiving and discharging material, an apron movable between a lowered position closing said bowl front and a raised position opening said front, laterally spaced apronsupporting arms each having one end pivotally connected to a respective bowl side wall on a first transverse horizontal axis, the other end of each of said arms being pivotally connected to said apron on a second axis parallel to said first axis, adjustable operating means operatively plvotally connected to said bowl on said first axis and to said apron at a point spaced from said first and second axes whereby said means may be operated to pivotally adjust and retain said apron in a plurality of posi- 3 tions relative to said arms, and means carried by said vehicle and connected to said apron for selectively moving the latter about said first axis between said lowered and raised positions.

2. A vehicle comprising a drawn scraper bowl having laterally spaced side walls upstanding from a transversely extending floor having a forward cutting edge and defining therewith an open bowl front for receiving and dis charging material, an apron movable between a lowered position in which it substantially engages said cutting edge for closing said bowl front and a raised position opening said front, laterally spaced apron-supporting arms each having one end pivotally connected to a respective bowl side wall on a first transverse horizontal axis, the other end of each of said arms being pivotally connected to said apron on a second axis parallel to said first axis, a pair of adjustable operating means each being operatively pivotally connectedtto a bowl side wall on said first axis and to said apron at a point spaced from said first and second axes whereby said means may be operated to pivotally adjust and retain said apron in a plurality of positions relative to said arms, and means carried by said vehicle and connected to said apron for selectively moving the latter about said first axis between said lowered and raised positions.

3. A vehicle comprising a drawn scraper bowl having laterally spaced side walls upstanding from a transversely extending floor and defining therewith an open bowl front for receiving and discharging material, an apron movable between a lowered position closing said bowl front and a raised position opening said front, laterally spaced apron-supporting arms each having one end pivotally connected to a respective bowl side wall and the other end pivotally connected to said apron, a fluid-operated jack operatively pivotally connected to said apron and to said bow on an axis aligned with the axis of pivotal connection of said arms to said bowl side walls whereby said jack may be operated to pivotally adjust and retain said apron in a plurality of positions relative to said arms, and means carried by said vehicle and connected to said apron for selectively moving the latter about said axis between said lowered and raised positions.

4. A vehicle comprising a drawn scraper bowl having laterally spaced side walls upstanding from a transversely extending floor and defining therewith an open bowl front for receiving and discharging material, an apron movable between a lowered position closing said bowl front and a raised position opening said front, laterally spaced apron-supporting arms each having one end pivotally connected to a respective bowl side wall and the other end pivotally connected to said apron, a pair of fluidoperated jacks each being operatively pivotally connected to said apron and to said bowl on an axis aligned with the axis of pivotal connection of said arms to said 'bowl side walls whereby said jacks may be operated to pivotally adjust and retain said apron in a plurality of positions relative to said arms, and means carried by said vehicle and connected to said apron for selectively moving the latter about said axis between said lowered and raised positions.

5. A vehicle comprising a drawn scraper bowl having laterally spaced side walls upstanding from a transversely extending floor having a forward cutting edge and defining therewith an open bowl front for receiving and discharging material, an apron movable between a lowered position in which it substantially engages said cutting edge for closing said bowl front and a raised position opening said front, laterally spaced apron-supporting arms each having one end pivotally connected to a respective bowl side wall on a first transverse horizontal axis, the other end of each of said arms being pivotally connected to said apron on a second axis parallel to said first axis, a pair of fluid-operated jacks each being operatively pivotally connected to a bowl side wall on said first axis and to said apron at a point spaced from said first and second axes whereby said jacks may be operated to pivotally adjust and retain said apron in a plurality of positions relative to said arms, and means carried by said vehicle and connected to said apron for selectively moving the latter about said first axis between said lowered and raised positions.

6. In combination, a tractor, a scraper bowl drawn by said tractor and including laterally spaced side walls and a transversely extending floor having a forward cutting edge, said walls and cutting edge defining an open front, an apron movable between a lowered position substantially engageable with said cutting edge for closing said bowl front and a raised position out of engagement with said cutting edge for opening said front, a pair of laterally spaced apron-supporting arms, each of said arms having its rearward end pivotally connected to said bowl side wall on a transverse horizontal axis, the other end of each of said apron-supporting arms being pivotally connected to said apron on another transverse horizontal axis, a pair of fluid-operated jacks contained substantially in the planes of said arms, each of said jacks having one end pivotally connected to a respective bowl side wall on the axis of pivotal connection to the latter of its associated apron-supporting arm, the other end of each of said jacks being pivotally connected to said apron at a point spaced above the axis of pivotal connection of said apron to said apron-supporting arms, whereby said jacks may be actuated to pivotally adjust said apron relative to said apron-supporting arms about its axis of connection to the latter and retain said apron in an adjusted position, and means operatively connected to said apron to control the position of the latter between said raised and lowered positions irrespective of its adjusted position relative to said apron-supporting arms.

7. In combination, a tractor, a scraper bowl including laterally spaced side walls and a transversely extending floor having a forward cutting edge, said walls and cutting edge defining an open bowl front, a drawbar including a forward hitch connection to said tractor and a pair of laterally spaced pull arms forming a yoke embracing said bowl side walls, the rearward ends of said pull arms being pivotally connected, respectively, to said bowl side walls on a transverse horizontal axis, means on said drawbar operatively connected to said bowl for lowering and raising said cutting edge between digging and carrying positions, an apron movable between a lowered position substantially engageable with said cutting edge for closing said bowl front and a raised position out of engagement with said cutting edge for opening said front, a pair of laterally spaced apron-supporting arms, each of said arms having its rearward end pivotally connected to said bowl side wall on a transverse horizontal axis, the other end of each of said apron-supporting arms being pivotally connected to said apron on another transverse horizontal axis, a pair of fluid-operated jacks, each of said jacks having one end pivotally connected to a respective bowl side wall on the axis of pivotal connection to the latter of its associated apron-supporting arm, the other end of each of said jacks being pivotally connected to said apron at a point spaced above the axis of pivotal connection of said apron to said apron-supporting arms, whereby said jacks may be actuated to pivotally adjust said apron relative to said apron-supporting arms about its axis of connection to the latter and retain said apron in an adjusted position, and means on said drawbar operatively connected to said apron to control the position of the latter between said raised and lowered positions irrespective of its adjusted position relative to said apron-supporting arms.

References Cited in the file of this patent UNITED STATES PATENTS 2,214,240 Allin Sept. 10, 1940 2,301,158 Daniels Nov. 3, 1942 (Other references on following page 7 UNITED STATES PATENTS Austin 2 Sept. 14, 1943 Robb Mar. 12, 1946 Vaughn -2-.- May 7, 1946 Rapp et a1. Jan. 9, 1951 5 Lindquist Aug. 21, 1951 Wagner June 23, 1953 Robb May 25, 1954 Fryer et a1. Dec. 11, 1956 Wardle June 18, 1957 

